However, there's another thought that arises from Tory glee over the Unite row. Are the Conservatives enjoying union-bashing too much?

Unite has about 1.4 million members. Total union membership in the UK is around 6 million. I repeat, 6 million, roughly one tenth of the population.

Keep that figure in mind. Watching PMQs today, you might well get the impression that the Conservative Party believes that membership of a trade union is essentially malign, that anyone associated with such an organisation is basically a bad person.

This is curious, to say the least, for a party whose hopes of winning a majority at the next election depend on winning the support of people who live in the north of this country and who work in lower-skilled jobs. In other words, the sort of people who are more likely than average to join a trade union.

Now, I realise that trade union members are, almost by definition, less inclined to vote Conservative than the average voter. But does that mean that no one who's a union member can ever be persuaded to vote Tory?

Tories aren't going to win the votes of trade unionists by suggesting, as they sometimes do, that they represent a "reds under the bed" threat. Instead, they have to make clear that they value the role unions play and understand the need for workers to have security in the workplace while disagreeing with the overblown rhetoric of union bosses.

Senior Tories could be speaking to the annual Trades Union Congress. Margaret Thatcher led a drive to build up Conservative Trade Unionists, which once had some 250 branches, and it seems perverse that such an organisation isn't given proper support today.

If PMQs is anything to go by, Mr Cameron is intent on ignoring such sensible advice and effectively writing off several million of the votes that might give him a majority at the next election. A curious choice.